A power wheelchair typically consists of two drives with drive wheels, aligned along a horizontal axis, normal to the direction of forward motion. The drives are attached to a frame structure. Also supporting the frame is typically a single or plurality of idler wheels or caster wheels. Also attached to the frame is a seat. A power source, typically batteries, supplies the electrical energy used to propel the drives. The batteries are typically located within the frame.
Some power wheelchairs are configured with the drive wheels centrally located about the longitudinal axis of the power wheelchair. Such wheelchairs are referred to as a mid-wheel drive wheelchairs or a center-drive wheelchairs. Center-drive wheelchairs are beneficial to the rider in that they have superior maneuverability when compared with power wheelchairs configured with either front or rear wheel drive systems. Stabilization of such wheelchairs usually requires the use of an augmentative system such as caster or idler wheels. Stabilization casters or idler wheels prevent unwanted tipping about the power wheelchair's pitch axis, in either the forward or rearward direction. On a center-drive power wheelchair, these caster or idler wheels are typically found both in front of, and behind the drive wheels. It would be advantageous if there could be developed an improved mid-wheel drive wheelchair whereby the chair is both maneuverable and able to ascend and descend obstacles typically encountered when driving.